With new and improved surgical techniques developed over recent years in operations involving the heart, lungs and chest of the patient there has been increased usage of what is known as the heart-lung machine. With many of these new surgical techniques the length of time during which a heart-lung machine is used is also increasing. In simple terms the heart-lung machine comprises a pump for the blood and an oxygenator for placing oxygen and releasing carbon dioxide from the blood. The blood which is circulated in such a machine is that of the patient and in some instances transfused blood may also be added. In the cardiopulmonary bypasss line there is placed a filter to remove undesirable material from the blood before the blood is returned to the patient. The filter not only removes undesirable materials which are present in the blood but is also used as a means to remove entrapped gas or air bubbles that are present in the blood.
We have discovered a new filter assembly which does an excellent and positive job of removing microbubbles of gas from the bloodstream. Also our new improved filter assembly unexpectedly reduces the harmful effects which filtration and degasification may have on blood.